Some conventional vehicles include a power source and a power train for transferring power to drive members. The power train often includes a transmission coupled to the drive members, which propel the vehicle. Some of those vehicles may include a system that limits the amount of torque transferred from the power source to the drive members in order, for example, to prevent excessive wear or failure of power train components that might occur under certain operating conditions. Such systems, however, may unduly inhibit the vehicle's performance, for example, when those operating conditions do not exist.
In particular, it may be desirable for some vehicles to be able to supply more torque to one or more of the drive members under certain operating conditions than might be permitted by systems that limit the amount of torque transferred from the power source to the drive members. For example, it may be desirable to supply more torque to one or more of the drive members as the vehicle is executing a turn. It may also be desirable to supply more torque to one or more of the drive members when the vehicle encounters a situation such as, for example, a steep incline. It may also be desirable to limit the slip of the one or more drive members, even under circumstances in which more torque is desirable.
One example of a vehicle including a steering control system that changes engine power output based on steering input is described in U.S. Pat. No. 6,138,782 (“the '782 patent”) issued to Anderson et al. on Oct. 31, 2000. The '782 patent describes a steering control system for a tracked vehicle that includes an engine driven variable displacement steering pump, which drives a hydraulic motor. A control system senses steering wheel position, vehicle speed, engine speed and forward/reverse vehicle direction. As a function of these sensed inputs, a control signal is generated and is used to control the swashplate angle of an engine-driven variable displacement pump, which drives a steering motor, which, in turn, drives a differential track drive mechanism. The control system also determines a ratio of motor speed to vehicle speed and generates a powerboost signal when the ratio exceeds a threshold value. The powerboost signal is communicated to an engine controller, which causes the engine to increase its power output. This modifies the engine fuel delivery curve based on the steering system power requirement and increases the power available for turning the vehicle.
Although the vehicle described in the '782 patent includes a steering control system that provides increased power for turning the vehicle, the vehicle described in the '782 does not include a system or method for controlling slip of driving members of the vehicle.
The systems and methods disclosed herein may be directed to achieving one or more of the desires set forth above.